Electric furnace



Apfil 6, 1926.

` 1,579,476 M. D. DOMINGUEZ l ELECTRIC FURNACE Filed May 12, 1924 imam-sheet 1 .ET P` M. D. DOMINGUEZ ELECTRC FURNACE Fileday 12, 1924 5 sheets-sheet 2 April 6, 192e. www@ INI/ENTO? l irme/VH D 1,579,476 prll 6 1926. M D DoMiNGUEZ ELECTRIC FURNACE Filed May l2, 1924 5 Sheets-Sheet 5 April e, 192e. 1,579,476

M. D. DOMINGUEZ ELECTRIC FURNACE l Filed May 12, 1924 5 sheets-sheet 4 April 6 1926. k

M. D. DOMINGUEZ ELECTRI C FURNACE 5 sheets-sheet 5 Filed May l2, 1924 IN VEN T01? .'ZZDomnguez Manuel Patented Apr'. 6, 1926.

UNITED STATES PATEN? QFFQF..

MANUEL D. DOMINGUEZ, OF NEW ORLEANS, LOUISANA, ASSIG-NOR OF ONE-HALF TO CHARLES A. DENIS AND ONE-HALF TO GEORGE SARPY, BOTH OF NEV ORLEANS,

LOUISIANA.

ELECTRIC FURNACE.

Application filed May 12,

To all whom t may concern:

Be it known that l, l\L\NUnL l). DOMIN- oUnz, a citizen of Spain, and resident of New Orleans, in the parish of Orleans and State of Louisiana, have invented certain new and use-ful Improvements in Electric Furnaces, ot which the following is a speciication.

My invention relates to electric furnaces of a type adapted for heating rivets, solder ing-coppers, and other articles or objects, for melting metals which melt at moderate temperatures, and ior other purposes.

An important object orn the invention is to provide in a unitary appliance one or any reasonable plurality of heating compartments or receptacles, which may, if desired, be of different sizes or shapes, each receptacle having' its own resistance heating element, and each receptacle preferably also having its own controlling element, such as a switch, together with suitable circuits and suitable provision for electrical and heat-insulation. By the provision ot individual controlling switches any one or more of the heating receptacles or compartments can be operated at a time, and the consumption of current is therefore only that required for the particular work in hand.

Another object is to provide a convenient and improved arrangement of the parts or subordinate combinations oi an electric tui-nace, and especially to provide a box or compartment containing the heating compartments or receptacles, with suitable heatand electric-insulation and suitable circuit connections, and in combination therewith, suitable compartments conveniently arranged for heating-element terminal connections and tor switch and main conductor connections, with suitable bus bars and wiring in each of said compartments; and further to arrange or support the complete appliance in a convenient position for use and manipulation of the controlling elements, this being preferably a position in which the walls of the box or casing (which is usually in the forni of a rectangular prism) are inclined and not vertical or horizontal.

Another object is to provide conveniently manipulated ejectors for use when certain 1924. Serial No. 712,781.

objects, including rivets, rods, etc., are being heated.

The invention consists in structures and arrangement of parts realizing the above stated and other objects. The accompanying drawings suthciently illustrate certain exemplify/ing embodiments of the invention. After considering these embodiments, skilled persons will understand that many variations may be made -within the principles oie the invention, and I contemplate the employment ot any structures that are properly within the scope of the appended claims: y

Fig. l is an end elevation of the invention in one specific embodiment.

Fig. 2 is a front elevation of the same.

Fig. 3 is a vertical section.

Fig. t is a plan view ot one of the terminal or conductor boxes with the cover removed.

Fig. 5 is a plan view of the other terminal or conductor with the cover removed.

Fig. 6 is a tace or plan view of the'side ot the furnace on which the switches are located.

Fig. 7 is a fragmentary detail, in enlarged section, of a somewhat modified structure or arrangement ot parts.

Fig. 8 is a wiring diagram.

Fig. 9 is a detail view, in side elevation, of one particular form of conductor or bus bar.

1While novel features of the invention may be embodied in a device or appliance that has only a single heating chamber or com? partment, it is evident that for a great many purposes, such as heatingl rivets, itv is necessary to heat a plurality of the articles at a time, and the number which must be heated at one time depends on the rapidity with which riveting operations are performed; it is, therefore, usually desirable to provide a plurality, and usually a very considerable number, ot heating chambers or compartments in one substantially unitary or self-contained appliance.

For this purpose, therefore, a housing or box B is provided, usually et rectangular outline. lVhile the detail construction of this housing may, ot course, vary considen ably. in one suitable form as here shown, it consists et' outer or side plates l, 2 and 3, which may be oi' any suitable material, such as sheet iron or steel, of substantial thickness. While in some cases all of the side plates may be separate, in other cases it is convenient to form some of them as parts of a continuous sheet. For example, plates 1 and 2 may be portions of a continuous or' integral sheet, and this sheet may also have a wall portion 4 bent at a right angle to the portion 2, and parallel to the portion l, forming one of three metal walls of a heater housing or compartment H. The fourth side of this inner compartment is closed by a wall 5 Which is desirably composed of a sheet of asbestos or asbestos composition, 0r else by a plurality of parallel strips of such material, the ends of this sheet or of the sep arate strips being secured to angle bars G.

The walls or wall portions 1, 2, 3 and 4 are suitably braced or reinforced or secured together by angle bars 7, 8, 9 and 10.

The partition consisting of the sheet or strips 5, spaces or separates from the heating casing H a relatively shallow boi: or compartment 1V which may be conveniently identified as a heating-coil-terminal compartment.

At an upwardly presented side of the main housing or box B another relatively shallow chamber or 'compartment X is provided. rlhis may be conveniently identified as a wiring 'or switch-terminal compartment. rlhis consists of side and end strips 12', 13 and 14 of suitabl'e material, wiiich desirably is material having insulating and heat-resisting qualities, such as asbestos or asbestos composition, or a suitable substitute therefor. The longitudinal strips 12 and 13 are placed over thinner strips or sheets 16 and 17 which may be of similar material, and the strips 12 and 16, and 13 and 17 respectively, are secured to angle bars 8 and 9 by screws 1S. A cover plate 2O is provided, which usually is of asbestos or asbestos composition or similar material, and is secured by screws 21 to strips 12 and 13. The end enclosure of the main housing B consists of sheet metal end plates 24.

l/Vhile it is not necessary in all cases, for reasons which will appear from the following description, it is preferable in many in stances to support the main housing in an inclined or angular position as shown in Figs. 1, 2 and 3. For this purpose end supports or brackets 26 of strip metal are provided, these being substantially triangular and being dimensioned to support the furnace in the position shown without danger of overturning.

One of the upwardiy-inclined faces of the heating chamber H has a thick liner 30 of asbestos or asbestos composition or similar material. Plate 2 and the liner are provided with registering apertures 31, which desirably have an outward taper or flare, and are designed to give access to the individual heating -chambers or compartments. Each of these chambers,l consists of a tube 32 of suitable metal, preferably copper. These tubes may be variously dimensioned and shaped for various purposes. They may also have different cross-sectional shapes, depending on the purpose for which they are to be used. The present structure, chosen as an exainple,`is especially designed for heating rivets or soldering coppers, and it is therefore sufficient to show the heating tubes with round cross-section. llt is desirable to provide in one appliance, tubes or heating chainbers of different sizes, as clearly indicated in Figs. 3 and 2, the 4last named iigure showing apertures 31 of different diameters, to correspond with the different diameters of the heating tubes. rllhis provides for heating rivets or similar objects of dierent diameters. lVhcn designed for heating rivets, each tube, desirably, has Ian upper end portion 33 of enlarged diameter, and the aperture 31 corresponds to the diameter of this enlargement. The enlargen'ient 33 permits the formation of an annular shoulder 34 upon which the head 35 of a rivet rests While its shank or stem 36 fits closely within the main bore of the tube l32, to provide for the ready transfer of heat from the tube to the rivet.

The base of each tube 32 rests on a metal plate 40, and the upper end of each tube is formed with flanges or ears 41 which are secured to the liner 30 by screws 42 and nutsy 43, the plate 2 having apertures 43 to give access to the screw heads. li/Vlierev'er necessary or desirable, for the mechanical or electrical connections, suitable lo'ck washers are placed under nuts; for instance, nuts 43 may be secured by lock washers Such locking devices will not be further mentioned.

The base plates 40 have lateral extensions 46 which are apertured to accommodate screws 47, which are insulated from the plates 40 by bushings 48 of suitable insulating material. The 'screws serve to support and properly locate the base plates 40, and also serve as binding posts and conductors, as presently appears. `The base plates are properly spaced from partition 5 by nuts 49, upon which the bushings 48 rest, and the bushings and base plates 40 are locked in position by nuts 50.

Surrounding each heating tube is a layer of suitable insulating material 55, such as asbestos or asbestos paper, and at the upper end of this tube is an integral or sepaA rate flange or washer 56 of similar material underlying the bottom face of the tube shoulder 34.

A suitable heating element is located around the insulation 55 and is by it insulated from the heating tube, although the heating element is in very Aclose proximity to the tube. 1n a preferred example, as here shown, it consists of a double coil or helix of suitable wire, such as nichrome wire, wound about the insulating tube 55 in the manner shown. The two portions of the helix are connected at their upper end by a loop or bend 61, which is properly secured or located by a pin 62, which is usually insulated; or in some cases deiinite retention of the upper end of the double helix is unnecessary. The end of one portion or strand of the heating wire is suitably looped and passed about one et the adjacent binding screws 47 and secured by a nut 64, and the end of the other portion of the helix is looped and passed over the other adjacent binding screw 47 correspondingto the particular heating tube, and secured by a siniilar nut 64. An insulating sleeve 66 of material similar to that of sleeve 55 is wound or otherwise located about the heating element, and its upper end may he extended in some cases to enclose the upper enlarged tube portion 33.

The entire interior of the heating casing H is preferably filled with heat-resisting or heat-insulating material 70, which may be pulverized or shreaded asbestos.

Ejectors are desirably provided to facilitate the removal of objects, such as rods or rivets, from the heating tubes. These comprise for each of the tubes a head of metal located within the heating tube and normally resting against the bottom thereof. A stem 76 passes through suitable apertures in plate 3, partition 5, and the base plate 40 ot' each tube, and also through an aperture in the tube base, and is secured to the head 75 in any convenient way, as by a rivet. On the outer end of each stem, in position convenient for manipulation, is a knob or handle 7 S, or fibre or other similar or suitable material, which resists conduction of heat :trom the stem 7 6. When it is not necessary or desirable to provide means for ejecting heated articles, the ejectors may, ot' course, be dispensed with; and especially if the heating tubes are to be used for melting metals, the bases of the tubes will be unapertured.

The wiring` for binding screws 47 is suiliciently explained in Fig, 5, which shows the wiring compartment W in section. A com` mon conductor or bus-bar 80, ot generally rectangular form, is provided, to make contact with onevoi the two binding screws' ot each heating element. Since the heating elements are, in this particular case, arranged in three horizontal rows, as best shown in Fig. 2, two side stretches 81 and82 of the bus-bar are arranged to make contact with the outward, or upwardly and downwardly located, terminals or binding screws 47 of the upper and lower rows of heating elements. The main portions of the stretches or strips S1 and 82 are arranged to lie close to the partition 5, and at suitable intervals the strips are bent to form upwardly eX- tending portions or loops 84 (see Fig. 9*) which are apertured to surround the binding screws. Nuts 86 are placed on the screws under the bus-bar members, to firmly lock them in position and in electrical contactV with the screws. The bus-bar portion 82 is also provided with extensions 88 properly arranged and bent to engage with one of the binding screws 47 of each ot the central row of heating elements, and the busebar extension ends are locked to these binding screws by nuts, in a similar manner to the arrangement just described.

Individual wires 90, 91 and 92, suitably protected by thick insulation 93, are provided for each of the other binding screws of each heating element, and the ends ot these wires are secured to screws by nuts, in an obvious way. All oiE the wires 90, 91 and 92 pass through apertures in plate 4, angle bar 9 and .insulating strip 17 into the wiring or switch connection boX X, Figs. 3 and 4. From the bus bar S0 a con` ductor 95, secured to the bus bar by a screw and nuts in an obvious way, and also provided with heavy insulation 96, passes through the walls and members above mentioned in connection with individual wires 90, 91 and 92, into compartment X, where the end ot the conductor 95 is secured to a.' binding screw 97, which passesthrough end wall 24 and is insulated from itby a bushing 98. The inner portion of the binding screw is located in box X, and the wire 95 is secured to it by nuts 99. rllhe outer portion of the binding screw is located in a small contact box (or main-terminal box) 100, detachably secured to the end wall 24.

Binding screw 97 is one oi the main terminals ot the heating appliance, and is adapted for connection to one ot' the two main or outside conductors which are led into thel bof: 100. The other main terminal ot the appliance is a binding screw 102A similarly arranged and located. From the inward portion ot this binding screw a wire 103 leads to a bus bar 104.

From bus bar 104, wires 105, 106 and 107, each go to one terminal or binding post of one of the series ot switches S, which may be standard snap switches having on and oti' positions, and which are secured to cover plate 20. rlhe other terminal or bind` 1 ing post of cach switch is connected to one of the wires 90, 91 or 92 previously mentioned', so that the circuit ot any heating element is completed (when the knob et its coriicsponding snap switch is properly positioned) by the internal switch contacts and two corresponding wires, such as 90- 105, 91-106 or 92H10? The switches, as best shown in 0, nre arranged in rows corresponding to the arrangement ot the heating tubes, and the switches and tubes may be correspondingly numbered or otherwise identified for the convenience oi? the operator. Thus, the switches as shown in Fig. 6 are numbered 1 to 1-, and the heating tubes are identii'ied by sin'iilar numbers applied the cover plate or wail 2, adjacent the apertures 3i.

rlhe tilted Vor inclined arrangement ol the complete appliance, previmasiy referred to, and well shown in Figs. 1, 2 and 3, is very iniportant and desirable because it provides tor the positioning oi" the heeiug tubes so that rivets or other articles may be prickly andr easily inserted in them and will then remain in position by gravity with the heads or outer ends ot the rivets or rods, in a position conrenient Yfor inspection through the apertures 31. The appliance is also elevated sunicientiy so that the ejector lrnobs 78 may be easily grasped and moved to eject the heated articles, which, when partly projecting trom the apertures 31, are in position tor convenient gi sping withv tongs. rlhe switches S are also conveniently piesented in an upward and accessible position for 'control of the individual heating unit circuits. V

1n the diagrammatic Fig. 3, the internal wiring and switches are properly indentilied. This ligure also shows a suitable ei:- ternal power source and ti.ansi"`oi'in.er with suitable external wiring ior one particular arrangement. An alternator 120 (which might otherwise be a direct current generator) has main wires 121 and 122 lea/- ing through fuses 123 to a double-pole switch 124e. rlhe switch terminal wires are in circuit with the primary 125 of a suitable transformer. llhe transtormer secondary 126 is divided into sections, with wires leading to contact points 12'?, 123, etc., ot a suitable controller 132. From the movable contact ot the controller a wire 133 is connected to binding post 102, and trom one end ot the secondary 126 a wire 132 goes to the binding post 97 previously mentioned.

The type oi' core construction ot the transformer can be varied as desired, or as may be required, for the type or" alternator or generator employed. 1When a transformer is used it can be adjusted in an obvious way, depending on the service desired ot the heater, or depending on the nature oit the resistance elements. For use with a direct current generator, any known or suitable rheostat or regulator may be employed. lt may, 'ot course, be necessary to adjust the rheostat or controller 132 in accordance with the number ot heating elements which are in circuit at any time.

Fig. 7 shows certain inodilications. The heating tube 3L is somewhat shorter and of larger diameter than in Fig. 3, being designed particularly to accommodate a soldering copper C of considerable diameter 'and relatively short. While for use in heating soldering coppers, having' han'dles, no ejector would be necessary, the heating tube may be, ot course, used :for large and short rivets or otl'ier cylii'idrical objects, and an ejector is thereliore shown, 'which niay be 'used when desired. The heating tube in this example is so short that it does not reach nearly to the partition 5. The base plates l() 4used in the previous example are therefore modiiied so that they consist ot angle strips 4G having portions resting against the bases ot the heating tube* and having other portions or ears 40 located near partition 5 and secured to the binding` posts 47, as in the previous e-:Janipe l claim 1. An electric heater comprising a metal heating tube, insulation thereon, a resistance wire wound about the insulation, circuit connections for the wire, and an ejector coniprising head within the tube 'and normally located at the tube bottoni, a stein passing through the tube bottom, and a handle laccessible for operation of the ejector.

2. An electric heater comprising a metal heating tube, iiisulation thereon, a resistance wire wound about the insulation, circuit connections 'tor the wire, and an ejector coinprisin a head within the tube and normally located at the tube bottom, a stem passing through the tube bottom and secured to the head, and a handle of heat-insulating mate-` rial on the outward end ot the stem and acoessible for operation ot the ejector.

3. An electric heating appliance 'comprising a heating casing, a plurality ot metal heating tubes of 'diiierent diameters therein, a resist'ai'ice wire located about each tube, and circuit rconnections for the wire.

1i. An electric heating appliance comprising` a heating casing, a plurality ot' metal heating tubes of diiilerent sizes therein, a resistance wire located about each tube, individual circuits tor the wires, and switch in each ot said circuits to control the application et current to the wire from an `outside source of energy.

5. An electric heating appliance compris-- ing a heating casing, a plurality of metal heating tubes' of diii'erent diameters therein, a resistance wire located about each t'ube, individual circuits for the wires, and a switch in each ot said circuits to control the application of current to the wire from an outside source ot energy.

G. An electric heating appliance, comprising a heating` casing, a plurality ot metal heating tubes therein, a resistance wire located about each tube, a terminal casing adjacent the heating casing, binding` posts having portions located in each of the casings, connections between the ditl'erent binding posts and 'ends of the dili'erent resistance Wires, and circuit connections to the binding posts located in said terminal casing.

7. An electric heating appliance, comprising a heating casing, a plurality of metal heating tubes of different sizes therein, a resistance wire located about each tube, a terminal casing adjacent the `heating casing, binding posts having portions located in each of the casings, connections between the diiierent binding posts and ends of the different resistance wires, and circuit connections to the binding posts located in said terminal casing.

8. An electric heating appliance, comprising a heating casing, a plurality of metal heating tubes of different diameters therein, a resistance wire located about each tube, a terminal casing adjacent the heating casing, binding posts having portions located in each of the casings, connections between the different binding posts and ends of the different resistance wires, and circuit connections to the binding posts located in said terminal casing.

9. An electric heating appliance, comprising a heating casing, a plurality of metal heating tubes therein, resistance wire located about each tube, a terminal casing adjacent the heating casing, binding posts having portions located in each of the casings, connections between the different binding posts Vand ends of the different resistance wires, circuit connections to the binding posts located in said terminal casing, said circuit connections including a bus bar com mon to one binding post of each of the resistance wires, and separate conductors for the other binding posts of the resistance wires.

10. An electric heating appliance, comprising a heating casing, a plurality of metal heating tubes therein, a resistance wire located about each tube, a terminal casing adjacent the heating casing, binding posts having portions located in each of the casings, connections between the different binding posts and ends of the different resistance wires, circuit connections to the binding posts located in said terminal casing, a c onnection casing adjacent the binding casing, switches thereon corresponding to the individual heating tubes, and circuit connections .in the last named casing connecting the individual switches with the individual binding post wires, and with a common conductor t-o provide for outside electrical connection.

11. An electric heater comprising a heating casing, a terminal casing at one side thereof, a switch connection casing at another adjacent side thereof, switches mounted exteriorly on the switch connection casing, a plurality of heatingtubes in the heating casing, a resistance wire for each heating tube, and connections leading through the terminal casing to the switch connection casing to provide for connection of in'dividual resistance wires to an outside source of electrical energy.

12. An electric heater comprising a heating casing, a terminal casing at one side thereof, a switch connection casing at another adjacent side thereof, switches mounted exterior-ly on the switch connection casing, a plurality of heating tubes in the heating casing, a resistance wire for each heating tube, connection leading through the terminal casing to the switch connection casing to provide for connection of individual resistance wires to an outside source of electrical energy, and an ejector for each heating tube comprising a head within the tube,

stem passing through the tube bottom, and a handle on the stem located outside the terminal casing.

13. An electric heating appliance, comprising a casing of generally rectangular form, including a plurality of heating tubes, heating elements therefor, one side of the casing having openings registering with the tubes, individual switches in circuit with individual heating elements and located on an accessible wall of the casing, and ejectors having handles accessibly located adjacent another wall of the casing.

14. An electric heating appliance, comprising a casingy of generally rectangular form, including a plurality of heating tubes, heating elements therefor, one side of the casing having openings registering with the tubes, individual switches in circuit with individual heating elements and located on an accessible wall of the casing, and ejectors having handles accessibly located adjacent another wall of the casing, and supporting means for the casing arranged to support it with its walls in inclined positions and with the apertures, switches and ejector handles located conveniently for access or manipulation. Y

15. An electric heating appliance, comprising a hea-ting casing, a plurality of individual heating tubes therein, a wall of the casing being apertured to give access to the tubes, insulation for the tubes, a heating element for each tube, circuitconnections for the heating elements, a heat-insulating filler in the casing substantially surrounding the tubes, and partitions of insulating material adjacent upper and lower sides of the casing.

1G. An electric heating appliance, comprising a heating casing, a plurality of individual heating tubes of different sizes therein, a wall of the casing being apertured to give access to the tubes, insulation for the tubes, a heating element for each tube, circuit connections for the heating elements, a heateinsulating filler in the substantially surrounding the tubes, and parfir titions of insulating material adjacent upper and lower sides of the casing.

` 17. An electric heating appliance, comprising a heating casing, a plurality of individual heating tubes of different diameters therein, a wall of the casing being apertured to give access to the tubes, insulation for the tubes, a heating element for each tube, circuit connection's for the heating elements, a heat-insulating filler in the casing substantially surrounding the tubes, and partitions of insulating material adjacent upper and lower sides of the casing.

18. An electric heating appliance, comprising a heating casing, a plurality of invdividuafl heating tubes therein, a wall of the casing being apertured to give access to the tubes, insulation Jfor the tubes, a heating element for each' tube, circuit connections for the heating elements, a heat-insulating liller in the casing substantially surrounding the tubes, partitions of insulating material adjacent upper and lower sides of the casing, a heating-element-terminal casing at one side of the heating casing adjacent one oi the insulating partitions thereof, and conducting members extending through said partition and having electrical connections to the heating elements within the heating casing and having conductor connections within the terminal casing, one of said connectionsl being a b us bar serving a plurality of said conducting members.

19 An electric heating appliance, com prising a heating casing, a. plurality of individual heating tubes therein, a wall of the casing being apertured to give access to the tubes', insulation for the tubes, a heating element for each tube, circuit connections for the heating elements, a heat-insulating filler in the casing Substantially surrounding the tubes, partitions of insulating material adjacent upper and lower sides of the casing, a switch ternjiinal casing at one side ojf the heating casing, a plurality oi switches eX'- teriorly mounted on the switch terminal casing, insulating strips in ,the switch terminal casing, a bus bar on one of the strips, connections 4from the bus bar to the switches, and individual connections troni one terminal of each heating element to one terminal of the corresponding switch.

20. vAn electric heating appliance, compr'sing'f-a heating Cashier," p uralty et in di idual heating tubes therein, a wall of the casing being apertured to give access t0 the tubes, insulation for the tubes, a heating element for each tube, circuit connections for the heating elements, a heat-insulatingliller in the casing substantially surrounding the tubes, partitions ot insulating material adjacent upper and lower sides ot the casing, a heating-element-terminal casing at one side of the heating casing adjacent one of the insulating partitions thereof, conducting members extending through said partition and'having electric connections to the heat ing elements within the heating casing and having conductor connections within the terminal casing, one 01"' said connections being a bus bar serving a plurality ot' said conducting members, a switch terminal cas` ing at another adjacent side of the heating casing, a. plurality of switches'exteriorly mounted on the switch terminal casing, insulating strips in the switch terminal casing,y a bus bar on one oli the strips, con-,- nections from the bus bar to the switches, and individual connectionsv from one terminal of each heating element to one terminal of the corresponding switch.

2,11. An electric heating appliance, coinrrsne' heating Gesine, e plurality 0f individual heating tubes therein, a wall of the casing being apertured to give access to the tubes, insulation for the tubes, a heat? ing element for each tube, circuit connections 'for the heating elements, a heat-insulating filler in the casing substantially surroundf ing the tubes, partitions of insulating material adjacent upper and lower sides ot the casing, aswixtch terminal casing at one side of the heating .Casina a plurality Of Switches @Xtel'orly mounted 0,11. the .Switch terminal casina insulating Strips in the Sivit-@l1 terminal casing, a bus bar on one ot the strips, connections from the bus bar to the switches, individual connections from onel terminal ot each heating element to one terminal Qt the corresponding switch, a detachable outsideoonnecton casing and Contact lnembel therein, extending into the switch terminal Casing and providing for electrical connection of outside conductors to the heating elements 'through the switches.

22. An electric 'heating appliance, comprising a heating casing, a plurality of individual heating tubes therein, a wall of the casing being apertured to give access 4to the tubes, insulation tor the tubes, a heating element for each tube, circuit connections for the heating elements, a heat-insulating iiller in the casing substantially surrounding thc tubes, partitions ot insulating material adjacent upper and lower sides of the CnS-lng', a heating-element-terminal casii'lg at one side of the heating casing adjacent one oi' the inU sulating partitions thereof, conducting meinbers extending through said partition and having electric connections to the heating elements Within the heating casing and having conductor connections within the terminal casing, one of said connections being a bus bar serving a plurality oi said conducting members, a switch terminal casing at another adjacent side ot the heating casing, a plurality of switches eXteriorly mounted on the switch terminalV casing, insulating strips in the switch terminal casing, a bus bar on one of the strips, con-k nectione from the bus bar t0 the Switches, individual connections from one terminal of each heating element to one terminal of the coi-responding switch, a detachable outside-connection casing and Contact member therein, extending into the switch terminal casing and providing for electrical connection of outside conductors to the heating elements through the Switches.

Signed at New Orleans, in the-parish of 10 Orleans and State of Louisiana, this 6th day of May, A. D. 1924.

MANUEL D. DOMINGUEZ. 

